Tony couldn’t remember ______he had turned off the computer before he left the office．
| A．that | B．where |
| C．when | D．whether |
The reason he was absent from class was his mother fell ill this morning.
| A．for; that | B．why; that | C．for; because | D．why; because |
The leader of the factory told us that very little ______ was made of the waste material in the past.
| A．cost | B．value | C．use | D．matter |
_____ of the students who took part in the military training is 450.
| A．A number | B．A lot | C．A few | D．The number |
—How many times have you been to China?
—In fact, it is the first time that I__________ here.
| A．was | B．have been | C．had been | D．am |
—I missed the first part of the film. It was really a pity.
—You __________ home half an hour earlier.
| A．should go | B．must have gone |
| C．should leave | D．should have left |